Auras
Many modern Real Time Strategy have hero units, single units that are powerful, but limited in number (usually only one of a single type allowed). In addition to their normally very high stats, many heroes also have auras which confer beneficial status effects or attribute bonuses to any friendly units that enter within a certain radius of the hero. This makes the hero unit an important factor in an engagement as, in addition to their formidable combat skills and powerful abilities, they also make the units around them more effective.
Some heroes and spellcaster units can also confer or inflict buffs, debuffs, and other status effects to units as spells.
Read more about this topic: Status Effect